SEALANT COMPOSITION

Provided is a sealant composition that can ensure good sealing properties while suppressing a flow of a sealant during travel and that can provide such performance in a well-balanced, compatible manner. As a sealant composition constituting a sealant layer (10) disposed in an inner surface of a pneumatic tire, a sealant composition in which a proportion (A) of toluene insoluble occupying the sealant composition is from 30 mass% to 60 mass% is used, or a sealant composition in which a ratio (d1/d2) of measured specific gravity (d1) of the sealant composition measured by an underwater replacement method to calculated specific gravity (d2) of the sealant composition calculated from specific gravity and a blended amount of each raw material in the sealant composition is from 0.7 to 0.9 is used.